1. Technical Field
The present invention relates to a technique of reducing flickers and burn-in in displaying a three-dimensional (3 dimensions, hereinafter, abbreviated as “3D”) video.
2. Related Art
The following technique is proposed to display a gradation in an electro-optical device having a liquid crystal element in a pixel. That is, there is proposed a technique of displaying an intermediate gradation by digitally turning a pixel either ON or OFF for each of a plurality of subfields into which one frame (one field) is divided and by changing a ratio of the turn-on (or -off) time.
In order to prevent burn-in of liquid crystal elements in the digital driving, a technique of inverting the polarity in a field a plural number of times and making the writing polarity of a subfield constituting a certain field inverse to the writing polarity of a subfield constituting the next field, (for example, see JP-A-2010-271611) and a technique of making the turn-on time with positive polarity equal to the turn-on time with negative polarity in one frame (for example, see JP-A-2010-85955) are proposed. In addition, there is also proposed a technique of increasing the number of displayable gradations as compared with the number of subfields by using the fact that the optical response speed of the liquid crystal element is relatively low (for example, see JP-A-2003-114661).
In recent years, apart from normal videos (2D), 3D video display is attracting more and more attention. Various 3D video display systems are proposed, and in general, a so-called 3D glasses system is used. Specifically, with the alternate display of a right eye image and a left eye image, the right eye portion of 3D glasses is made opaque when a left eye image is displayed, and the left eye portion of the 3D glasses is made opaque when a right eye image is displayed. According to the 3D glasses system, a viewer wearing 3D glasses visually confirms a left eye image only with the left eye and visually confirms a right eye image only with the right eye. Accordingly, it is possible to perceive that a displayed video has depth and is three-dimensional.
However, when a 3D video is displayed by digital driving, the number of subfields increases in order to display a left eye image and a right eye image, and thus it is difficult to express multi-gradation (gradation property). Furthermore, in an electro-optical device such as a liquid crystal display device, it is necessary to drive a left eye image and a right eye image with both polarities without generating a polarity difference.